Double action directional fluid flow valve

ABSTRACT

A double action directional fluid flow valve includes a stepped piston connected with a poppet valve and moveable by a controller between open and closed positions by applying a continuous pressure to a small diameter piston face and selectively applying and removing pressure from a large diameter piston face to move the poppet valve between an open position and a closed position.

RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.12/205,148 filed on Sep. 5, 2008, now U.S. Pat. No. 8,256,738 issued onSep. 4, 2012, which claims the benefit of U.S. Provisional ApplicationNo. 60/993,649 filed on Sep. 13, 2007.

FIELD OF THE INVENTION

The present invention relates to direction control valves and, inparticular to a fluid flow valve having affirmatively actuated pistonscontrolling poppet valves for the selective routing of fluids.

BACKGROUND OF THE INVENTION

Direction control valves are available in many formats for controllingthe flow of fluids between sources and applications. For mere on/offcontrol, ball and poppet valves are effective and widely employed. Whereflow rates, pressure drops, and other characteristics are desired, gate,butterfly, pressure regulating, needle control valves and other wellknow valve type are used. Combined with the need to handle diversefluids, including gases, fluids, slurries of varying compositions, thenumber of available valves is substantial requiring dedicated toolingwith little interchangeability of components.

In our pending patent application, U.S. Ser. No. 10/223,236 filed onAug. 19, 2002, there is disclosed a flow control valve that can bemanufactured in a wide range of valve sizes without dedicated toolingand requires minimal variations to handle gases and liquids at varyingpressures and flow rates. Therein, a poppet valve assembly is carried ina two-piece valve body formed by conventional machining. The poppetvalve assembly includes a non-spring biased piston isolated from fluidflow. The pilot actuated piston shifts a poppet valve to a closedposition around a flow orifice to block fluid flow. Removing pilotpressure allows the fluid flow to shift the valve to an open position.The poppet valve accommodates flow orifices of varying sizes. Thus, bymerely changing the orifice size, differing pressures and flow rates canbe handled allowing a commonality of components. The valves could alsobe interconnected to provide multi-port functionality. Notwithstandingthe increased flexibility and functionality, these poppet valves, likeothers, provide only on/off control at prevailing conditions inprescribed flow paths between ports. Control of vacuum applications wasnot possible.

It would accordingly be desirable to utilize the benefits of our abovevalve in applications of directional flow control not currently enabled.

SUMMARY OF THE INVENTION

The present invention provides a double action fluid flow valvecontrolling a poppet valve and enabling functions and features of othervalve types not previously available while retaining the benefitsafforded by our prior design. Fluids, under pressure and vacuum, arereadily handled. Flow and flow rates may be regulated and modulated.Reverse flow may be controlled. Valve response times may be regulated toavoid line shock. Pilot pressure may be provided internally orexternally. Affirmative poppet piston control may be provided intwo-way, three-way or multi-way functionality. In addition, the valvemay be compactly incorporated into fluidic cylinders improving responsetimes and reducing operating costs.

In one aspect, the present invention provides a fluid flow valveincluding a body member having flow ports interconnected by a floworifice surrounded by an annular planar valve seat normal to anoperating axis; a stepped piston counterbore in said body member spacedfrom and coaxial with said valve seat, said piston counterbore having anopen end and a closed end; a valve guide sealing said open end of pistoncounterbore and having an opening therethrough coaxial with saidoperating axis; a stepped piston slidably supported in said pistoncounterbore coaxial with said operating axis, said piston forming afirst chamber between said piston and said closed end of said pistoncounterbore and a second chamber between said piston and said valveguide; a poppet valve member having a stem extending through saidopening in said valve guide and coaxially operatively connected to saidpiston for concurrent movement between an open position and a closedposition, said poppet valve member having an enlarged head sectionhaving a sealing surface normal to said operating axis for engaging saidvalve seat in said closed position at a sealing interface; and acontroller for selectively pressurizing and depressurizing said secondchamber while maintaining pressurizing of said first chamber therebymoving said piston and said poppet valve between said open position andsaid closed position. The valve functions under pressure and vacuumconditions to provide bidirectional piston actuation without springs.

In additional aspects the maintaining pressurizing of the first chamberis provided by an external pressure source and may be directly connectedwith said first chamber. The maintaining may also be provided by aninternal pressure communicated from a passage in said body memberbetween at least one of said ports and said first chamber. Thepressurizing of said first chamber may be provided by internal pressureis communicated from passages in said body member between both of saidports and said passages include check valves whereby the highestpressure in the ports is communicated to said first chamber. A stopmember in said first chamber may be axially adjustable to limit movementof said piston thereby controlling the flow between said ports in saidopen position.

Additionally, the fluid flow valve may include a flow control device foradjustably controlling said pressurizing and said depressurizing of saidsecond chamber. A pressure regulator operatively associated with saidcontroller for adjustably controlling said pressurizing of said secondchamber and the pressure regulator may provide a pressure in said secondchamber less than said first chamber whereby fluid flow forces betweensaid ports modulate poppet valve position to control fluid flowtherebetween.

Further, the fluid flow valve include three-way functionality and theports may be an inlet port between said valve guide and said orificethereof and a outlet port, an exhaust flow port in said valve bodyfluidly connected with said outlet port at an exhaust flow orificesurrounded by an annular planar exhaust valve seat normal to anoperating axis; a cylindrical second piston counterbore in said bodymember spaced from and coaxial with said exhaust valve seat, said secondpiston counterbore having an open end and a closed end; a second valveguide sealing said open end of second piston counterbore and having anopening therethrough coaxial with said operating axis; a cylindricalsecond piston slidably supported in said second piston counterborecoaxial with said operating axis, said second piston forming a firstchamber between said second piston and said closed end of said secondpiston counterbore and a lower chamber between said second piston andsaid second valve guide; a second poppet valve member having a stemextending through said opening in said second valve guide and coaxiallyoperatively connected to said second piston for concurrent movementbetween an open position and a closed position, said second poppet valvemember having an enlarged head section having a sealing surface normalto said operating axis for engaging said exhaust valve seat in saidclosed position at a sealing interface; and a controller forconcurrently selectively pressurizing and depressurizing said secondchamber of first piston while maintaining pressurizing of said firstchamber and for depressurizing said first chamber of said second chamberthereby moving said pistons and associated poppet valves in phaseopposition between said open positions and said closed positions.

In a further aspect, the fluid flow valve may be directly incorporatedin a fluidic cylinder at each end plate member of a fluidic cylinderhaving a pair of spaced end plate members, a piston sleeveinterconnecting the end plate members and having a piston reciprocablysupported a chamber wherein said piston includes a shaft operativelyextending through one of the end plate members, said piston dividingsaid chamber into a retraction chamber pressurized to retract said shaftinto said chamber and an extension chamber pressurized to extend saidshaft from said chamber, and said controller is operative with saidfluid flow valve in each end plate member to pressurize said chambers inphase opposition to thereby retract and extend said shaft.

For improved isolation of the poppet piston from the fluid, first andsecond sealing members are carried by said valve guide and engage saidvalve stem, and a passage in said valve guide applies pressure betweensaid sealing members for resisting fluid leakage from said ports to saidsecond chamber, by example fluidly connection with said first chamber.

In yet another aspect, the invention provides a fluid flow valveincludes: a body member having flow ports interconnected by a floworifice surrounded by an annular planar valve seat normal to anoperating axis; a stepped piston counterbore in said body member spacedfrom and coaxial with said valve seat, said piston counterbore having anopen end and a closed end; a valve guide sealing said open end of pistoncounterbore and having an opening therethrough coaxial with saidoperating axis; a stepped piston slidably supported in said pistoncounterbore coaxial with said operating axis, said piston forming afirst chamber between said piston and said closed end of said pistoncounterbore and a lower chamber between said piston and said valveguide; a poppet valve member having a stem extending through saidopening in said valve guide and coaxially operatively connected to saidpiston for concurrent movement between an open position and a closedposition, said poppet valve member having an enlarged head sectionhaving a sealing surface normal to said operating axis for engaging saidvalve seat in said closed position at a sealing interface; a firstpassage in said body member fluidly connected with one of said ports anda second passage in said body member fluidly connected with the other ofsaid ports; and a controller for selectively alternatively fluidlyconnecting said first passage and said second passage with said firstchamber.

In yet a further aspect, the present invention provides a fluid flowvalve including: a body member having flow ports interconnected by aflow orifice surrounded by an annular planar valve seat normal to anoperating axis; a stepped piston counterbore in said body member spacedfrom and coaxial with said valve seat, said piston counterbore having anopen end and a closed end; a valve guide sealing said open end of pistoncounterbore and having an opening therethrough coaxial with saidoperating axis; a stepped piston slidably supported in said pistoncounterbore coaxial with said operating axis, said piston forming afirst chamber between said piston and said closed end of said pistoncounterbore and a lower chamber between said piston and said valveguide; a poppet valve member having a stem extending through saidopening in said valve guide and coaxially operatively connected to saidpiston for concurrent movement between an open position and a closedposition, said poppet valve member having an enlarged head sectionhaving a sealing surface normal to said operating axis for engaging saidvalve seat in said closed position at a sealing interface; a firstpassage in said body member fluidly connected between one of said portsand said first chamber; a stop member carried by said body memberaxially adjustably positioned in said first chamber and having a sealingmember engagable with said piston in a closed position at a sealinginterface and spaced from said piston in an open position; a ventpassage in said piston member and said valve guide and fluidlyconnecting said other of said ports and said first chamber when saidsealing member of said stop member is in said open position and fluidlydisconnecting said other of said ports and said first chamber when saidsealing member of said stop member is in said closed position; andspring means for biasing said piston toward said closed position withsaid sealing member of said stop member.

In yet an additional aspect, the present invention provides a fluid flowvalve including: a body member having flow ports interconnected by aflow orifice surrounded by an annular planar valve seat normal to anoperating axis; a stepped piston counterbore in said body member spacedfrom and coaxial with said valve seat, said piston counterbore having anopen end and a closed end; a valve guide sealing said open end of pistoncounterbore and having an opening therethrough coaxial with saidoperating axis; a stepped piston slidably supported in said pistoncounterbore coaxial with said operating axis, said piston forming afirst chamber between said piston and said closed end of said pistoncounterbore and a lower chamber between said piston and said valveguide; a poppet valve member having a stem extending through saidopening in said valve guide and coaxially operatively connected to saidpiston for concurrent movement between an open position and a closedposition, said poppet valve member having an enlarged head sectionhaving a sealing surface normal to said operating axis for engaging saidvalve seat in said closed position at a sealing interface; a stop membercarried by said body member axially adjustably positioned in said firstchamber; a spring member between said stop member and said piston forbiasing said poppet valve to said closed position; and a controller forselectively pressuring said chamber to move said poppet valve to saidclosed position.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the invention will becomeapparent upon reading the following description taken in conjunctionwith the accompanying drawings in which:

FIG. 1 is a side view of a double action directional fluid flow valve inaccordance with an embodiment of the invention;

FIG. 2 is a side cross sectional view of the fluid flow valve in theclosed position taken along line 2-2 in FIG. 1;

FIG. 3 is a side cross sectional view of the fluid flow valve of FIG. 2in the open position;

FIG. 4 is a side cross sectional view of the actuator body of the fluidflow valve of FIG. 1;

FIG. 5 is a side cross sectional view of the valve body of the fluidflow valve of FIG. 1;

FIG. 6 is a side cross sectional view of the poppet valve assembly ofthe fluid flow valve of FIG. 1;

FIG. 7 is a side cross sectional view of another embodiment of theinvention;

FIG. 8 is a side cross sectional view of another embodiment of theinvention;

FIG. 9 is a side cross sectional view of another embodiment of theinvention;

FIG. 10 is a side cross sectional view of another embodiment of theinvention;

FIG. 11 is a side cross sectional view of another embodiment of theinvention;

FIG. 12 is a side elevational view of another embodiment of theinvention;

FIG. 13 is a cross sectional view taken along line 13-13 of FIG. 12;

FIG. 14 is a side cross sectional view of another embodiment of theinvention;

FIG. 15 is a side elevational view of the embodiment of FIG. 14;

FIG. 16 is a cross sectional view taken along line 16-16 in FIG. 15;

FIG. 17 is a side elevational view of another embodiment of theinvention;

FIG. 18 a cross sectional view of the valve of FIG. 17 showing the valvein the exhaust position;

FIG. 19 is a cross sectional view showing the valve of FIG. 17 in thesupply position;

FIG. 20 is a fragmentary cross sectional view of an embodiment of theinvention;

FIG. 21 is a side cross sectional view of another embodiment of theinvention showing the valve in the closed position;

FIG. 22 is a side cross sectional view showing the valve of FIG. 21 inthe open position;

FIG. 23 is a side cross sectional view of another embodiment of theinvention; and

FIG. 24 is a side cross sectional view of another embodiment of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings and FIG. 1 through 3, there is shown a doubleaction directional fluid valve 10 in accordance with a preferredembodiment for controlling the flow of fluid between fluid source 12 anda fluid application 14. The valve 10 is configured in the embodiment asa two way valve, however, it will become apparent that otherconfigurations and features may be incorporated as described in greaterdetail in the additional embodiments described below. It will also beapparent that the valve may be used for fluids in gaseous or liquidstates and under pressure or vacuum conditions.

The fluid control valve 10 comprises a two-part body member including abase or valve body 20 and a cover or actuator body 22 operativelycarrying a double piston poppet valve assembly 24 operated by acontroller 26. The valve 10 functions to prevent the flow of fluid fromthe source 12 in the closed position of FIG. 2, and permit the flow offluid from the source 12 between an inlet port 28 and an outlet port 30to the application 14 in the open position of FIG. 3. The valve 10 alsofunctions to prevent flow back through the port 30 into the port 28.

Referring to FIG. 6, the poppet valve assembly 24 comprises a steppedpiston 40 connected to a poppet valve 44 that is slidably supported inassembly by a valve guide 46. The piston 40 includes a cylindrical basesection 50 of a major diameter D1 and a top section 52 of a lesser minordiameter D2. The diameters of the piston 40 are relatively sized toprovide a double action actuation for positive opening and closing,without supplemental springs, to control flow, the sizes being dependenton the specifics of the flow control application. The top section 52includes an outwardly opening annular groove in an outer surface forretaining a sealing element 54, such as an O-ring. The base section 50includes an outwardly opening annular groove in an outer surface forretaining a sealing element 56, such as an O-ring. The poppet valve 44includes a cylindrical stem 57 and an enlarged generally cylindricalvalve disc or valve member 58. The upper end of the stem 57 includes athreaded axial hole. The stem 57 is coaxially received with a press fitin a downwardly opening counterbore in the base section 50 of the piston40. A through hole including an upper counterbore is formed in the topsection 52 of the piston and intersects the lower counterbore. Athreaded fastener 59 is received therein with the shank threaded to thevalve stem 57 to fixedly connect the poppet valve to the piston, afterassembly with the valve guide 46. The poppet valve 44 is thus coaxiallyconnected with the piston for movement along an operational axis 60(FIG. 2). The valve member 58 includes a planar circular lower surface62 normal to the axis of the stem. A downwardly opening annular grooveis formed in the lower surface for carrying a sealing element 64, suchas an O-ring. A plurality of grooves may be provided whereby a commonpoppet valve may be used with appropriate sealing elements for use withvarying sized orifices. The poppet valve is thus face seated and thestem and valve member are exterior of the flow orifice. A rear seatedconfiguration may also be used.

The valve guide 46 is a circular disc having an outer flange having anouter diameter coaxial with a center bore. The flange carries on theupper surface thereof a sealing element 65 for sealing with an opposedplanar bottom surface of the actuator body. The stem of the poppet valvehas a close sliding fit with the center bore of the valve guide foradditionally maintaining coaxial movement in assembly. The center boreincludes an inwardly opening annular groove for retaining a sealingelement 66, such as an O-ring, for sealing the valve stem.

Referring to FIG. 5, the valve body 20 includes an upwardly openingstepped counterbore 66. The counterbore 66 is intersected with thelateral inlet port 28 connected to the fluid source. The lateral outletport 30 is formed below the counterbore 66. An annular flow orifice 72is formed coaxially in the base of the counterbore 66 and serves tofluidly interconnect the ports. An annular valve seat 74 is formed inthe counterbore base around the orifice 72 for providing a sealinginterface with the sealing element 64 of the poppet valve 44 (FIG. 6). Apilot passage 76 is formed in the valve body having an inlet connectedto a source of pilot pressure 75 and an outlet at the top surfacethereof for fluid connection with a passage in the actuator body 22 asdescribed below.

Referring to FIG. 4, the actuator body 22 includes a downwardly openingstepped counterbore 80. The actuator body 22 and valve body 20 arefixedly connected with suitable fasteners, not shown, for clamping theopposed planar surfaces together with the counterbore 80 in the actuatorbody coaxial with the counterbore 66 in the valve body 20. Thecounterbore 80 includes a base section 81 having a diameter providing aclose sliding fit with the base section of the piston 40, and a topsection 82 having a close sliding fit with the top section of thepiston. It will thus be appreciated that, in assembly, the poppet valveis constrained at four coaxially locating surfaces; the pistoninterfaces, the valve guide bore, and the press fit of the valve stemwith the piston. This maintains the critical perpendicular movement ofthe valve with respect to the valve seat to insure positive planarcontact therebetween.

A pilot passage 84 in the actuator body includes a downwardly openingsection registering with the pilot pressure passage in the valve bodyconnected with a lateral section having an outlet at the base of the topsection 82 of the counterbore 80. A second or upper chamber passage 86in the actuator body includes a lateral section having an inlet at thebase of the top section of the counterbore 80 connected with a verticalsection having an outlet in the top surface. A third or lower chamberpassage 87 in the actuator body has a lateral section intersecting thebase section of the counterbore adjacent the rim thereof connected witha vertical section exiting at the top surface. A fourth or middlechamber passage 88 in the actuator body has a lateral sectionintersecting the base section of the counterbore adjacent the basethereof connected with a vertical section exiting at the top thereof. Afifth or vent passage 89 intersects passage 88 and provides an exhaustport to the exterior.

In assembly, the piston in the closed position of FIG. 2 establishes anupper chamber 90 between the top of the piston and the base of the uppersection of counterbore, an intermediate middle chamber 92 between thepiston sections and the base of the base section of the counterbore, anda lower chamber 94 between the piston and the valve guide. The upperchamber 90 is thus fluidly connected with passages 82, 84, the middlechamber 92 with passage 88, and the lower chamber 94 with passage 87.

The passages 84, 86, 88 are fluidly connected with the controller 26. Asuitable controller is a three-way solenoid valve. The controller 26 isselectively operative to pressurize and exhaust the lower chamber 94while maintaining pressure in the upper chamber 90. The normally closedinput port of the controller 26 is connected by line 96 with passage 84from the upper chamber 90. The passage from the lower chamber 94 isconnected with a normally open port by line 97, the outlet of which isconnected by lines 98 to the passage 88 and the vent passage 89.

In the closed position of FIG. 2, the upper chamber 90 is pressurized bythe pilot pressure and the middle and lower chambers 92, 94 are vented,whereby the pressure in the upper chamber shifts the piston 40 to thelower position whereat the poppet valve 44 seals the orifice 72preventing flow between the inlet port 28 and the outlet port 30 againstthe inlet pressure force at the orifice sealing interface. Theseconditions may be met through selection of the pilot pressure, thepiston section diameters and the orifice size. The orifice size, inparticular, may be selected handle a wide range of the source pressureswhile retaining a base construction for the actuator assembly and pilotpressure. When the controller is oppositely conditioned, both the upperand lower chamber are pressurized from the pilot source 75, with thediametral differences between the piston sections providing a net upwardforce shifting the poppet valve to the open, raised position of FIG. 3allowing flow between the ports. It will be appreciated that theselective pressure conditions in the chambers may be provided byindependent pressure sources of the same or differing pressure.

The foregoing fluid control valve provides a rapid response times inboth directions. For closing, the exhausting of the larger lower chambermomentarily pressurizes the middle chamber resulting in an additionaldownward force on the middle chamber piston area thereby increasing therate of closure. For opening, the flow to the lower chamber creates apressure drop in the upper chamber, increasing the opening force andresponse time. Further, the venting is unidirectionally outward. Nonegative pressures in the chamber occur during actuation. This preventsentry of exterior contaminants that can foul the valve parts and allowsoperation under formerly unfavorable conditions.

In the following embodiments, common components use their priornumerical designation. Referring to FIG. 7, the pilot pressure may beprovided by the internal pressure at the ports. The flow control valve100, as described above and using prior numerical designations for thecomponents, may be provided with a passage 102 connecting the inlet port28 with the passage 84 in the actuator body. The passage 102 may includea spring biased check valve 104. The passage 102 may be provided with anexisting pilot connection with an exterior source, by capping the samewith a plug 106. Another passage 110 including a check valve 112 isprovided from the outlet port 30 wherein a passage communicates with theupper chamber 90 and the passage 88 to the controller 26. Thisarrangement provides a pilot pressure that is the highest of thepressures experienced steadily or transiently in either port therebypreventing back leakage regardless of port pressures. The flow directionabove may be reversed.

Another embodiment of the invention is shown in FIG. 8 wherein thedouble action directional fluid flow valve is provided with a flowcontrol. The basic valve 120 may be the same as described above whereinthe poppet valve 44 is shifted downwardly to a closed position to seatthe valve under either external pilot pressure or internal pressure. Thevalve is reversely conditioned to the open position by applying pressureat passage to the lower chamber 94 thereby shifting the poppet valveupwardly. The valve 120 includes a flow control assembly 122 comprisinga piston stop 124 having an enlarged head 125 disposed in the upperchamber 90 and a cylindrical shank 126 slidably extending through anaxial hole in the base of the actuator body 22 and received in an axialbore of an adjustment bracket 127 attached to the top of the actuatorbody. The upper portion of the bore is threaded and receives and anadjustment screw 128. The adjustment screw may be manually adjusted toraise or lower the head 125 of the piston stop 124. Such adjustment, inturn, varies the limit of upward piston travel, and accordingly the flowthrough the orifice. The adjustment screw may also be coupled to anelectromechanical actuator for remote control of the flowcharacteristics. In either case, the flow control assembly allowsdynamic adjustment of the flow characteristics, enabling the valve 120to respond similar to a mechanical ball valve in varying flow ratesduring operation.

A further embodiment of the invention is shown in FIG. 9 wherein thedouble action directional fluid flow valve is provided with a responsecontrol. The basic valve 130 may be the same as described above whereinthe poppet valve 44 is shifted downwardly to a closed position to seatthe valve under either external or internal pilot pressure. The valve isreversely conditioned to the open position by applying pressure atpassage to the lower chamber 94 thereby shifting the poppet valveupwardly. The valve 130 includes a flow control assembly 132 comprisinga needle valve or flow control screw 134 positioned in a passage for thelower chamber 94 at the intersection of passage sections. The needlevalve 134 is threaded into a lateral threaded hole and has a manuallyadjustable tip position effective for varying the pilot flow from theupper chamber 90 through the controller 26 to the lower chamber 94 tothereby adjustably control the opening rate of the poppet valve as thelower chamber is pressurized. The valve 134 also serves to control thevalve closing by restricting the venting of the lower piston chamber.

The response control overcomes shock and damage due to sudden pressureincreases when the valve is opened or closed. Such shock or hammeringeffects caused by rapidly shifting valves are particularly harmful inliquid flow applications that require some type of control to protectthe system. The response control may be operationally adjusted on siteto the requirements of the application.

A further embodiment of the invention is shown in FIG. 10 wherein thedouble action directional fluid flow valve is provided with a pressurecontrol. The basic valve 140 may be the same as described above using anexternal pilot pressure and wherein the inlet port 142 is below thepoppet valve and orifice 144 and the outlet port 145 is thereabove. Withthis arrangement the line from the upper piston chamber to thecontroller includes a pressure regulator 146. The pressure regulator 146may be manually or electromechanically controlled. In the closedposition, the pilot pressure in the upper piston chamber 90 is selectedto create a positive downward force to seat the poppet against thecounter force of the inlet pressure in inlet port 142 acting against thepoppet valve surface at the orifice and the valve remains closed. Toopen, the pressure regulator 146 is adjusted to provide a pressure tothe lower chamber 94 that is less than the pressure required to open thevalve on its own. In combination with the inlet port pressure, however,the opening force is greater than the force in the upper piston chamberwhereby the valve moves to the open position. As the pressuredifferential between the inlet port and the outlet port decreases, thevelocity pressure force on the poppet valve is decreased and when theupper piston chamber force overcomes the lower piston chamber force andthe diminished force on the poppet valve, the later is shifted towardthe closed position. This in turn regulates the down stream pressurewithout the use of a separate regulator in the outlet line. Thearrangement allows high speed and high flow pressure control.

Referring to FIG. 11, the basic valve as described above can also beconfigured to have inline inlet and outlet ports, 152 and 154,respectively, in the valve body 156 wherein the flow orifice 157 isformed in a horizontal base wall of the poppet valve counterbore andcommunicates with the port 154. The ports 152 may be a larger diametercounterbores thereby providing an increased flow capacity comparable toconventional larger high flow inline poppet valve with costly sand castbodies. The valve may be removed without disturbing the adjacent valveport blocks 158, 159. The port blocks can be ported with pipe threads orother convention connection methods.

The machined passages may be configured to provide further advantages.Referring to FIGS. 12 and 13, valves 160 as described above may beprovided with valve bodies 161 having axially aligned, seriallyconnected longitudinal through ports 162 and pilot ports 164 fluidlycommunicating with longitudinally spaced lateral ports 166 at orifices168, which are selectively and opened and closed by the double pistonpoppet valve assembly as described above. This arrangement permits thevalves to be directly connected without the conventional independentporting resulting in obvious size and cost advantages. Further, such anarrangement allows the fluid flow direction to be reversed. Thus fluidmay flow from a common source through ports 162 for selectivedistribution at ports 166, or delivered from plural sources at ports 166for common supply at ports 162.

The poppet and double piston arrangement may also be beneficiallyincorporated with three way functionality. Referring to FIG. 14, thereis shown a three way double action fluid flow valve 200. Therein, adouble piston poppet valve assembly 202 is operatively coupled with asingle piston poppet valve assembly 204 to provide three-way control offluid from an inlet port 206 to an outlet port 208 controlled by valveassembly 202, and from the outlet port 208 to an exhaust port 210controlled by valve assembly 204.

The valve assembly 202 is controlled as described above wherein a pilotpressure is maintained in the upper chamber 212 through passage 214 froma check valved internal source 216. An external source as describedabove may also be used. The upper chamber 212 is connected to a threeway controller 216 at passage 218 and line 220. In the closed position,the lower chamber 226 is vented at passage 228, and lines 230 and 232 atthe controller 216 to vent passage 234, 236. In the open position, thecontroller 216 is reversely conditioned and the lower chamber 226 ispressurized while maintaining pressure in the upper chamber 212 therebyraising the double piston assembly 202 to the open position andpermitting fluid flow from the inlet port 206 to the outlet port 208.

The valve assembly 204 includes a single piston 240 supported in acounterbore in the actuator body that is operatively connected to apoppet valve 242 and valve guide 244. The upper chamber 246 of the valveassembly 204 is connected through passage 248 to the passage 228 fromthe lower chamber 226 of the double piston valve assembly 202 andaccordingly is pressurized and exhausted therewith. The lower chamber250 of the valve assembly 202 is connected to the vent passage 234 andaccordingly continuously vented.

In operation, when the valve assembly 202 is conditioned open, the lowerchamber 226 and the upper chamber 246 above the single piston arepressurized while maintaining pressure in the upper chamber 212, wherebythe single piston is shifted to the closed position whereat the poppetvalve seals the orifice 262 to the exhaust port. When the double pistonis conditioned closed at the controller, the lower chamber 226 and theupper chamber 246 of the single piston are vented whereby fluid pressurefrom the outlet port 208 raises the poppet assembly 204 and piston tothe open position enabling fluid flow from the outlet port 208 to theexhaust port 210. Thus three way functionality is provided compactlywith a single control and a unitized multiple piston valve assembly.

The three way functionality may also be provided in a modular in-lineformat as shown in FIGS. 15 and 16 wherein the inlet ports 270 areaxially aligned, the exhaust ports 272 are axially aligned, and thepilot ports 274 are axially aligned. The ports are independentlyconnected with respective outlet ports 278 and the fluid flow theretoand therefrom controlled by the above described valve assemblies toindependently control fluid flow with respect to inlet orifices andexhaust orifices.

The three way functionality of the double action fluid flow valve mayalso be incorporated into conventional pneumatic or hydraulic cylindersto provide energy savings, increase cylinder actuation speeds, and canbe used as a redundant safety valve or as a booster valve for furtherincreases in actuation speed. Therein the end caps of the cylinders aremachined to provide the valve body with desired porting and the actuatorbody and poppet valve assembly assembled thereto and removed therefromfor installation, replacement and service. The above features andcontrols may be incorporated for operation.

An illustrative embodiment for incorporation with a conventionalpneumatic cylinder is illustrated in FIGS. 17-19. Therein, a cylinder300 includes a cylindrical piston sleeve 302 having a rod end plate 304and a cap end plate 306. A piston 308 is slidably supported in thesleeve 302. A shaft 310 extends through the end plate 304 and isoperatively connected with a piston 308 to be actuated thereby.Pressurize fluid is delivered to an extension piston chamber 312 betweenthe piston 308 and the cap end plate 306 to shift the piston 308 andshaft 310 to an extended position. Pressurized fluid is delivered to aretraction piston chamber 314 between the piston 308 and the rod endplate 304 to shift the piston and the shaft to the illustrated retractedposition.

A valve 320 for controlling the fluid input and exhaust from anassociated chamber is provided at each end plate 304, 306. Fordescription, the valve 320 will be described with respect to the rod endplate 304. Each end plate is a generally rectangular solid of sufficientthickness for accommodating the valve and includes at least one planarsurface for incorporation and mounting of the valve. Herein, the endplate forms the valve body and the actuator body 322 is attached theretoby suitable fastening means, such a mounting screws, not shown. Theactuator body 322 operatively carries a double piston poppet valveassembly 324 with a poppet valve 325 and a single piston poppet valveassembly 326 with a poppet valve 327.

The end plate 304 includes an inlet port 330 laterally drilled into aside of the end plate and extending beyond and below the valveassemblies. The port has an inlet for connection with a source ofpressurized fluid. The valve assembly 324 includes a stepped counterbore coaxial therewith having an outer section locating and supporting avalve guide 332 and base section. The counterbore includes a throughhole 334 extending from the base section and intersecting the inlet port330, and forming a flow orifice having an annular valve seat therearoundfor sealing with the poppet valve 325. A supply port 336 extends fromthe rear surface of the plate and intersects the base section forsupplying fluid in an open position to the piston chamber.

The valve assembly 326 includes a stepped counterbore coaxial therewithhaving an outer section supporting a valve guide 342 and a base section.A blind hole 344 extends downwardly from the base of the base section,and forming a flow orifice having an annular seating surfacetherearound. An exhaust port 346 extends from the rear surface of theplate and intersect the base section of the counterbore. A return port348 extends from the rear surface of the plate and intersects the hole344 and serves to return the actuating fluid to source or vent. In theopen position, fluid is exhausted from the piston chamber through theexhaust port for flow through the orifice and return or venting throughport 348.

The double piston poppet valve assembly includes a double diameterstepped piston 350 slidably supported in a downwardly opening steppedcounterbore coaxial with the orifice. The poppet valve 325 includes astem extending through an opening in the valve guide 332 and connectedto the piston 350. The poppet valve 325 includes an enlarged valve headhaving a sealing element on a lower surface engaging the valve seatingsurface about the orifice in the closed position to prevent flow fromthe inlet port 330 to the supply port 336 in the closed positionillustrated in FIG. 18 and permit flow therebetween in the open positionillustrate in FIG. 18. In assembly, the piston and counterbore establisha small diameter upper chamber above the piston, a larger diameter lowerchamber below the piston and between the valve guide, and anintermediate chamber between the piston and the lower section of thecounterbore. The upper chamber is continuously pressurized. In oneformat, the pilot pressure is supplied through a passage 360 between theinlet port and the upper chamber and an exterior port 362 closed oreliminated. The passage may include a check valve 364 for establishingthe highest pressure experienced in the inlet port. Alternatively or incombination, pilot pressure may be supplied through the exterior port.

The single piston poppet valve assembly includes a single diameterpiston 370 slidably supported in a downwardly opening counterborecoaxial with the orifice. The poppet valve 327 includes a stem extendingthrough an opening in the valve guide 342 and connected to the piston370. The poppet valve 327 includes an enlarged valve head having asealing element on a lower surface engaging the valve seating surfaceabout the orifice in the closed position to prevent flow from theexhaust port 348 to the port 346 in the closed position illustrated inFIG. 19 and permit flow therebetween in the open position illustrate inFIG. 18. In assembly, the piston 370 and counterbore establish an upperchamber 326 above the piston, and a lower chamber 366 including a ventbelow the piston and between the valve guide. The upper chamber 326 ofthe single piston and the lower chamber of the double piston are fluidlyand serially connected to a passage 378 having an outlet 380 at the sideof the actuator body and connected by line 370 to a fluid controller 372such as a solenoid valve. A flow control adjuster 386 as described in aprior embodiment includes a stop member for adjustably controlling theopen position of the single piston for adjusting the flow rate iscontinuously pressurized.

In operation, fluid under pressure is continuously supplied to inletports 330 of both cylinder rod end plate 304 and cap end plate 306 andthe valves 320 therefor are operated in phase opposition. Forretracting, the shaft and cylinder piston, at the extension chamber 314,the double piston valve assembly is shifted to the open position and thesingle piston valve assembly is shifted to the closed position.Accordingly, on the cap end valve 320 the upper chamber is pressurizedat passage 360, and the controller vents the lower passage of the doublepiston valve assembly and the poppet valve is shifted by the forcedifferential to the closed position, and the fluid flow from port 348 to346 forces the single piston valve assembly to the open position,thereby exhausting fluid from chamber 312. Concurrently, the other valveon the rod end plate is reversely condition delivering fluid to chamber314 and moving cylinder piston 308 to the retracted position. Forextending, the controller/372 on the rod and cap ends are shiftedwhereby the valves 320 reverse operation, as described above, and thecylinder is extended.

In both conditions, it will be noted that the fluid delivery paths arecompactly located on opposing sides of the poppet valves, therebysignificant reducing line losses and providing faster response times. Afurther increase in response times may be provided by incorporating abooster circuit 380 as shown in FIG. 19. Therein, a lateral booster port382 is provided in the end plate 304. The port 382 is connected to afluid source 384. A longitudinal secondary supply port 386 intersectsthe port 382 and fluidly connects the associated piston chamber with thefluid source. The port 382 includes an associated flow control member384 that establishes a parallel flow path in concert with the doublepiston valve to supplement fluid flow to the piston cylinder therebyincreasing response time. A similar booster port may be incorporated onthe cap end plate.

For mixed fluid applications using pneumatic actuation for controllingliquids, the above described valves may be provided with a positivebarrier for preventing admixture during operation. Referring to FIG. 20,this feature may be provided utilizing the pilot pressure. Therein, thevalve 400 includes a valve guide 402 having two axially spaced sealingmembers 404 engaging the stem 406 of the poppet valve 408. A radialpassage 410 is formed in the valve guide 402 having an outlet betweenthe sealing members 404 and an outlet at the outer flange connectingwith a passage 422 in the valve body 418 fluidly connected with a pilotpressure passage 421 in the actuator body 418. A check valve 420 isprovided in the valve guide operative to admit pilot pressure and blockreverse flow of fluid and/or air. Alternatively the check valve may belocated at other passage locations intermediate pilot source and theseals.

The above described poppet valve assembly may also be used to provideaffirmative flow control in fluid applications using either a doublepiston or a single piston design. The following embodiments aredescribed with reference to a single piston, however, it will beunderstood that the features may be obtained with double stepped pistonconfigurations.

Referring to FIGS. 21 and 22, there is shown a flow control valve 450provided with an anti-back flow capability. The valve 450 includes a twopiece housing having an actuator body 452 connected with a valve body454 by suitable fasteners, not shown. The valve body 454 includes aninlet port 456 aligned with an outlet port 458 fluidly interconnected ata flow orifice 460 therebetween at the base of an upwardly openingcounterbore. A single piston poppet valve assembly 462 includes a piston463 connected with a poppet valve 464 supported by a valve guide 466.The valve assembly 462 is selectively operated by a controller 468, suchas a three way solenoid, for movement between the illustrated loweredclosed position (FIG. 21), and a raised open position (FIG. 22) whereatfluid flows from the inlet port 456 to the outlet port 458 through theorifice 460. Referring to FIG. 22, the valve is operated by an internalpilot pressure delivered through a passage 470 from the inlet port tothe inlet line 472 to a normally closed port at the controller 468. Apilot passage 474 from the upper chamber above the piston is connectedwith a normally open port of the controller that is connected by line476 with a passage 478 in the actuator body and valve body having anoutlet at the outlet port 458. Referring to FIG. 21, the controller 468is actuated to deliver pilot pressure through passage 470, thecontroller and passage 474 to the upper chamber 480 above the pistonthereby providing an actuating force moving the poppet valve to theclosed position at the sealing interface surrounding the orifice 460against the static fluid pressure on the poppet valve 464. In the openposition, the upper chamber is vented through passage 474, thecontroller and passage 478 to the outlet port 458. Under flowconditions, as the pressure differential decreases and therebyincreasing the outlet port pressure, the outlet pressure is transmittedto the upper chamber. This increase in pressure causes a progressiveclosing of the poppet valve that is effected before pressureequalization between the ports thereby preventing a reverse flow throughthe valve.

A single or double piston poppet valve assembly may also be employed toassist operation of a mechanically actuated two way valve with aninternal back pressure check. Referring to FIG. 23, a fluid controlvalve 500 includes an axially adjustable piston stop assembly 502 havingan enlarged piston stop 504 that is manually or electromechanicallycontrolled by operator 506 to regulate travel of the piston 508 tocontrol the position of the poppet valve 510 of a poppet valve assembly512 with respect to a sealing interface around a flow orifice 514 froman inlet port 516 to an outlet port 518 between an open position,intermediate positions, and a closed position. A pilot passage 514extends from the inlet port 516 to the chamber 520 above the piston 508.Downwardly extending compression spring members 522 are retained betweenthe lower end of the piston and the top end of the valve guide 524 andprovide an upward biasing force on the piston 508. The piston 508 andthe valve guide 524 include axial through passages 530, 532. The pistonstop 504 includes an annular sealing element, such as an O-ring, thatengages the top surface of the piston and is effective for sealing thepassages 530, 532 in an engaged position.

In the mechanically closed position, the stop 504 engages the piston 508and pilot pressure is provided through passage 514 to the upper chamber520, resulting in an affirmative force greater than the static force atthe orifice and the biasing force of the spring members 522. As thepiston stop is raised, the pilot pressure is bled through the passages530, 532 resulting in lessened downward force and the spring membersbias the piston and the poppet valve upwardly, opening the flow orifice.At the desired piston stop position, the piston reengages the pistonstop sealing the passages 530,532 and providing a stable condition. Toclose the valve, the piston stop is lowered sealing the passages530,532. During closure, the pressure in the chamber 520 provides themain downward force overcoming the spring and flow forces, therebysignificantly reducing the torque needed to move the piston head andproviding a flow control that simulates mechanically actuated ballvalves. In the desired position, the pressure on both sides of thepiston will be equalized and the piston and poppet will float.

A single or double piston poppet valve assembly may also be configuredto provide pressure reduction and back flow prevention in two wayvalves. Referring to FIG. 24, a flow control valve 600 includes anadjustable piston stop assembly 602, which in series with a springmember 604 biases the piston 606 of a poppet valve assembly 608 tomechanically move a poppet valve 608 toward a closed position forcontrolling fluid flow through a flow orifice 612 between an inlet port614 and an outlet port 616. The actuator body 618 includes a passage 620connected by line 622 with an outlet port of a controller 624, such as asolenoid valve. When being used as a mechanically actuated pressurereducing valve, the piston stop head 624 is lowered, acting on thespring member 604 and downwardly shifting the poppet valve 610 reducingthe flow through the orifice 612 from the inlet port 614 to the outletport 616. The poppet valve 610 permits fluid flow when the force on thepoppet valve is greater than the spring biasing force. As the pressuredifferential between the ports decreases, the force on the poppet valvedecreases and the spring force biases the poppet valve to the closedposition. The effect of the pressure differential is adjusted by theposition of the piston stop. If the pressure differential reverses, thepoppet valve is closed preventing fluid flow in a reverse direction. Thecontroller may be actuated to supply pilot pressure from source 630through line 622 to the piston chamber 634 to close the valve regardlessof the piston stop position. The controller is reversed to vent thechamber and return the pressure regulating and back flow preventionfeatures.

In will thus be appreciated that the present invention provides fordouble action fluid flow control in a poppet valve assembly whereinadditional features may be incorporated to provide operating controlsnot previously obtainable in such assemblies.

Having thus described a presently preferred embodiment of the presentinvention, it will now be appreciated that the objects of the inventionhave been fully achieved, and it will be understood by those skilled inthe art that many changes in construction and widely differingembodiments and applications of the invention will suggest themselveswithout departing from the sprit and scope of the present invention. Thedisclosures and description herein are intended to be illustrative andare not in any sense limiting of the invention, which is defined solelyin accordance with the following claim.

What is claimed:
 1. A fluid flow valve comprising: a body member havingflow ports interconnected by a flow orifice surrounded by an annularplanar valve seat normal to an operating axis; a stepped pistoncounterbore in said body member spaced from and coaxial with said valveseat, said piston counterbore having an open end and a closed end,wherein the stepped piston counterbore has a first portion having afirst diameter and a second portion having a second diameter greaterthan the first diameter; a valve guide sealing said open end of pistoncounterbore and having an opening therethrough coaxial with saidoperating axis; a stepped piston slidably supported in said pistoncounterbore coaxial with said operating axis, said piston forming afirst chamber between said piston and said closed end of said pistoncounterbore and a second chamber between said piston and said valveguide, wherein the stepped piston has a first portion having a firstdiameter and a second portion having a second diameter greater than thefirst diameter, and at least a portion of the first portion of thestepped piston is received in the first portion of the stepped pistoncounterbore and the second portion of the stepped piston is received inthe second portion of the stepped piston counterbore; and a poppet valvemember having a stem extending through said opening in said valve guideand coaxially operatively connected to said piston for concurrentmovement between an open position and a closed position, said poppetvalve member having an enlarged head section having a sealing surfacenormal to said operating axis for engaging said valve seat in saidclosed position at a sealing interface.
 2. The fluid flow valve asrecited in claim 1 wherein an external pressure source maintains saidpressurizing of said first chamber.
 3. The fluid flow valve as recitedin claim 2 wherein said external pressure source directly is connectedwith said first chamber.
 4. The fluid flow valve as recited in claim 2wherein an internal pressure pressurizes said first chamber and iscommunicated from a passage in said body member between at least one ofsaid ports and said first chamber.
 5. The fluid flow valve as recited inclaim 2 wherein an internal pressure pressurizes said first chamber andis communicated from passages in said body member between both of saidports, and said passages include check valves whereby the highestpressure in the ports is communicated to said first chamber.
 6. Thefluid flow valve as recited in claim 2 wherein said valve is adapted tobe operatively couple with supplemental valve of like construction,wherein said one of said ports is commonly aligned, and wherein saidvalves are adapted to be supplied with a common source of pressure forsaid first chamber.
 7. The fluid flow valve as recited in claim 1including a stop member in said first chamber axially adjustable tolimit movement of said piston, thereby controlling the flow between saidports in said open position.
 8. The fluid flow valve as recited in claim1 wherein said ports are axially aligned.
 9. The fluid flow valve asrecited in claim 1 wherein one of said ports extends through said bodymember, and the other of said ports is transverse to said one of saidports.
 10. The fluid flow valve as recited in claim 1 wherein said portsconsist of an inlet port between said valve guide and said orificethereof and a outlet port, an exhaust flow port in said valve bodyfluidly connected with said outlet port at an exhaust flow orificesurrounded by an annular planar exhaust valve seat normal to anoperating axis; a cylindrical second piston counterbore in said bodymember spaced from and coaxial with said exhaust valve seat, said secondpiston counterbore having an open end and a closed end; a second valveguide sealing said open end of second piston counterbore and having anopening therethrough coaxial with said operating axis; a cylindricalsecond piston slidably supported in said second piston counterborecoaxial with said operating axis, said second piston forming a firstchamber between said second piston and said closed end of said secondpiston counterbore and a lower chamber between said second piston andsaid second valve guide; a second poppet valve member having a stemextending through said opening in said second valve guide and coaxiallyoperatively connected to said second piston for concurrent movementbetween an open position and a closed position, said second poppet valvemember having an enlarged head section having a sealing surface normalto said operating axis for engaging said exhaust valve seat in saidclosed position at a sealing interface; and a controller forconcurrently selectively pressurizing and depressurizing said secondchamber of first piston while maintaining pressurizing of said firstchamber and for depressurizing said first chamber of said second chamberthereby moving said pistons and associated poppet valves in phaseopposition between said open positions and said closed positions. 11.The fluid flow valve as recited in claim 10 wherein said valve bodyincludes a base member including said ports and orifices and a covermember including said counterbore removably connected to said basemember.
 12. The fluid flow valve as recited in claim 11 wherein saidbase member is at each end plate member of a fluidic cylinder having apair of spaced end plate members, a piston sleeve interconnecting theend plate members and having a piston reciprocably supported a chamber,wherein said piston includes a shaft operatively extending through oneof the end plate members, said piston dividing said chamber into aretraction chamber pressurized to retract said shaft into said chamberand an extension chamber pressurized to extend said shaft from saidchamber, and said controller is operative with said fluid flow valve ineach end plate member to pressurize said chambers in phase opposition tothereby retract and extend said shaft.
 13. The fluid flow valve asrecited in claim 1 including first and second sealing members carried bysaid valve guide and engaging said valve stem, and a passage in saidvalve guide for applying pressure between said sealing members forresisting fluid leakage from said ports to said second chamber.
 14. Thefluid flow valve as recited in claim 13 wherein said passage is fluidlyconnected with said first chamber.
 15. The flow fluid valve as recitedin claim 1 including a controller for selectively pressurizing anddepressurizing said second chamber while maintaining pressurizing ofsaid first chamber thereby moving said piston and said poppet valvebetween said open position and said closed position.
 16. The fluid flowvalve as recited in claim 15 including a feature fluidly between saidcontroller and said second chamber for adjustably controllingpressurizing and depressurizing of said second chamber.
 17. The fluidflow valve as recited in claim 16 wherein said feature for adjustablycontrolling includes an adjustable valve member in a passage in saidbody member between said controller and said second chamber.
 18. Thefluid flow valve as recited in claim 15 including a pressure regulatoroperatively associated with said controller for adjustably controllingpressurizing of said second chamber.
 19. The fluid flow valve as recitedin claim 18 wherein said pressure regulator provides a pressure in saidsecond chamber less than said first chamber, whereby fluid flow forcesbetween said ports modulate a poppet valve position to control fluidflow therebetween.
 20. The flow fluid valve as recited in claim 1wherein the flow ports are coaxial.
 21. The flow fluid valve as recitedin claim 1 wherein the poppet valve member includes a planar circularlower surface normal to an axis of the stem of the poppet valve memberthat can contact the valve seat.
 22. A fluid flow valve comprising: abody member having flow ports interconnected by a flow orificesurrounded by an annular planar valve seat normal to an operating axis;a stepped piston counterbore in said body member spaced from and coaxialwith said valve seat, said piston counterbore having an open end and aclosed end, wherein the stepped piston counterbore has a first portionhaving a first diameter and a second portion having a second diametergreater than the first diameter; a valve guide sealing said open end ofpiston counterbore and having an opening therethrough coaxial with saidoperating axis; a stepped piston slidably supported in said pistoncounterbore coaxial with said operating axis, said piston forming afirst chamber between said piston and said closed end of said pistoncounterbore and a lower chamber between said piston and said valveguide, wherein the stepped piston has a first portion having a firstdiameter and a second portion having a second diameter greater than thefirst diameter, and at least a portion of the first portion of thestepped piston is received in the first portion of the stepped pistoncounterbore and the second portion of the stepped piston is received inthe second portion of the stepped piston counterbore; a poppet valvemember having a stem extending through said opening in said valve guideand coaxially operatively connected to said piston for concurrentmovement between an open position and a closed position, said poppetvalve member having an enlarged head section having a sealing surfacenormal to said operating axis for engaging said valve seat in saidclosed position at a sealing interface; and a first passage in said bodymember fluidly connected with one of said ports and a second passage insaid body member fluidly connected with the other of said ports; and acontroller for selectively alternatively fluidly connecting said firstpassage and said second passage with said first chamber.
 23. A fluidflow valve comprising: a body member having flow ports interconnected bya flow orifice surrounded by an annular planar valve seat normal to anoperating axis; a stepped piston counterbore in said body member spacedfrom and coaxial with said valve seat, said piston counterbore having anopen end and a closed end, wherein the stepped piston counterbore has afirst portion having a first diameter and a second portion having asecond diameter greater than the first diameter; a valve guide sealingsaid open end of piston counterbore and having an opening therethroughcoaxial with said operating axis; a stepped piston slidably supported insaid piston counterbore coaxial with said operating axis, said steppedpiston forming a first chamber between said piston and said closed endof said piston counterbore and a lower chamber between said piston andsaid valve guide, wherein the stepped piston has a first portion havinga first diameter and a second portion having a second diameter greaterthan the first diameter, and at least a portion of the first portion ofthe stepped piston is received in the first portion of the steppedpiston counterbore and the second portion of the stepped piston isreceived in the second portion of the stepped piston counterbore; apoppet valve member having a stem extending through said opening in saidvalve guide and coaxially operatively connected to said piston forconcurrent movement between an open position and a closed position, saidpoppet valve member having an enlarged head section having a sealingsurface normal to said operating axis for engaging said valve seat insaid closed position at a sealing interface; a first passage in saidbody member fluidly connected between one of said ports and said firstchamber; a stop member carried by said body member axially adjustablypositioned in said first chamber and having a sealing member engagablewith said piston in a closed position at a sealing interface and spacedfrom said piston in an open position; a vent passage in said pistonmember and said valve guide and fluidly connecting said other of saidports and said first chamber when said sealing member of said stopmember is in said open position and fluidly disconnecting said other ofsaid ports and said first chamber when said sealing member of said stopmember is in said closed position; and a resilient feature for biasingsaid piston toward said closed position with said sealing member of saidstop member.
 24. A fluid flow valve comprising: a body member havingflow ports interconnected by a flow orifice surrounded by an annularplanar valve seat normal to an operating axis; a stepped pistoncounterbore in said body member spaced from and coaxial with said valveseat, said piston counterbore having an open end and a closed end,wherein the stepped piston counterbore has a first portion having afirst diameter and a second portion having a second diameter greaterthan the first diameter; a valve guide sealing said open end of pistoncounterbore and having an opening therethrough coaxial with saidoperating axis; a stepped piston slidably supported in said pistoncounterbore coaxial with said operating axis, said stepped pistonforming a first chamber between said piston and said closed end of saidpiston counterbore and a lower chamber between said piston and saidvalve guide, wherein the stepped piston has a first portion having afirst diameter and a second portion having a second diameter greaterthan the first diameter, and at least a portion of the first portion ofthe stepped piston is received in the first portion of the steppedpiston counterbore and the second portion of the stepped piston isreceived in the second portion of the stepped piston counterbore; apoppet valve member having a stem extending through said opening in saidvalve guide and coaxially operatively connected to said piston forconcurrent movement between an open position and a closed position, saidpoppet valve member having an enlarged head section having a sealingsurface normal to said operating axis for engaging said valve seat insaid closed position at a sealing interface; a stop member carried bysaid body member axially adjustably positioned in said first chamber;and a spring member between said stop member and said piston for biasingsaid poppet valve to said closed position.